煤灰对氨气吸附特性的实验研究

选择性催化还原(SCR)和选择性非催化还原(SNCR)过程中未反应的氨被飞灰吸收,引起空预器堵灰或影响飞灰的二次利用。飞灰中的氨浓度与氨在飞灰中的吸附特性是密切相关的。以锡盟褐煤和阳泉无烟煤为研究对象,利用NH₃程序升温脱附(NH₃-TPD)技术研究了氨气的化学吸附与煤灰的矿物组成、成灰气氛、冷却速率和残炭量之间的关系。结果表明,快速冷却、还原性气氛会使煤灰中的玻璃体含量增加,促进氨的吸附;残炭表面的酸性官能团为氨提供了大量的吸附位点,使其吸附量明显超过矿物质灰样。

Experimental study on ammonia adsorption by coal ashes

Unreacted ammonia in Selective Catalytic Reduction (SCR) and Selective Non-catalytic Reduction (SNCR) technology may be adsorbed by fly ash and lead to ash blocking in the air preheater or hindering the secondary utilization of ash. Ammonia adsorption by fly ash may have a close relationship to the concentration of ammonia in flue gas. Regarding Ximeng lignite and Yangquan anthracite as the subjects investigated, NH₃ Temperature-programmed Desorption (NH₃-TPD) was utilized to study the relationship between ammonia chemical adsorption and mineral composition of the ash, the atmosphere of ash production, cooling rate of ash as well as the amount of residual carbon in the ash. The results show that rapid cooling and reduction atmosphere could increase the amount of amorphous phase in the ash and facilitate ammonia adsorption. On the other hand, ash with residual carbon could adsorb more ammonia than mineral ash as a result of acidic functional group on the surface of residual carbon.